Sheathed core



Jan. 16, 1940. s. BORGESON SHEATHED CORE 7 Sheet-Sheet 1 Filed Feb. 27. 1937 INVENTOR. SM/76y f. gr jeso/z A TTORNEY.

Jan. 16, 1940. s. E. BORGESON SHEA'I'HED CORE 7 Sheets-Sheet 3 Filed Feb. 27, 1937 INVENTOR. 50 450/2 \z ATTORNEY.

Jan. 16, 1940- s. E. BORGESO-N SHEATHED CORE 7 Sheets-Sheet 5 Filed Feb. 2'7, 1937 INVENTOR. .S/ahayf; 504m TTORNE).

Jan. 16, 1940. 5 5 BQRGESQN 2,187,391

SHEATHED CORE Filed Feb. 27, 19:57 7 Shegts-Sheet 1 nvvszv r012. Sway [.50/ esp/2 ATTORNEY Patented Jan. 16, 1940 UNITED STATES PATENT OFFICE SHEATHED coma Sidney E. Borgeson, Rome, N. Y., assignor to General Cable Corporation, New York, N. Y., a corporation of New Jersey Application February 27, 1937, Serial No. 128,250

2 Claims. (Cl. 174-122) This invention relates to cores provided with fibrous jackets, and more particularly to cores having thereon one or more seamless felted layers of intimately interentangled fibres. It is an object of the invention to provide cores having new and improved felted fibrous jackets. It also is an object of the invention to provide insulated electrical conductors having an improved construction and arrangement ofinsulating and protecting cover. Other objects and advantages of the invention will appear hereinafter.

This'application is a continuation-in-part of my copendingapplication for Method and apparatus for sheathing cores, filed July 27, 1932, Serial No. 625,174, now Patent No. 2,078,228, dated April 27, 1937, wherein a method and apparatus for producing the felted fibrous layers are claimed.

It will be apparent from the following description that the new felted fibrous covering may be applied to various types of cores, both flexible and rigid, solid and hollow, and having varying cross sections. Merely for convenience the invention will be described with reference particularly to insulated electrical conductors. Illustrative embodiments of the invention selected merely for descriptive purposes, and one suitable apparatus for applying the felted fibrous covering to the core are shown in the accompanying drawings, in which:

Fig. 1 is a view of a core having the new felted fibrous covering;

Figs. 2 and '3 are views of modified constructions, each comprising a core and the new felted fibrous covering;

Fig. 4 is a top plan view of a machine for applying a felted covering to cores such as electrical conductors;

Fig. 5 is an end elevation of the machine shown in Fig. 4, from the right-hand side of Fig. 4;

Fig. 6 is an end elevation of the machine from the left-hand side of Fig. 4;

Fig. 7 is a view substantially on the line 'l--'l of Fig. 5;

Fig. 8 is an enlarged vertical section substantially on the line 8-8 of Fig. 7;

Fig. 9 is a view of the applicator for applying fibres to an electrical conductor, substantially on the line 9--9 of Fig. 8;

Fig. 10 is an elevation of the separatng roll for tearing apart the fibres of a fleecy strand and for throwing the separated fibres on to the applicator;

Fig. 11 is an elevation of the feeding roll for feeding the fleecy strand to the separating roll;

Fig. 12 is a longitudinal section through another type of feeding roll; and

Fig. 13 is a partial section to enlarged scale substantially on the line l3|3 of Fig. 12. The legends applied to the drawings are by way of 5 illustration and not limitation.

It has been proposed heretofore to apply fibrous coverings to cores of various types, and to utilize fibrous coverings applied to electrical conductors as a part or all of the insulation. Various methods have been proposed for applying a fieecy strand of fibrous material to an electrical conductor to form an insulating jacket. Many of the methods of the prior art have not proven practical, either because the method of forming 15 the jacket produces an insulating wall having distinct seams which open up when the conductor is bent, or because of the difflculty and cost of especially preparing the fibrous material in a form suitable for application to the conductor with available apparatus.

Electrical conductors having fibrous coverings as known and used heretofore are open to a number of objections. The fibrous coverings often have been applied as helical or longitudinal wrappings of slivers or rovings which are pressed in place about the conductor. These coverings have seams which open readily when the conductor is bent or subjected to abrasion. Other coverings comprise merely a body of unfabricated fibres compressed about the conductor. In neither of these constructions do the fibres form a fabric layer having any substantial resistance to wear and tear, and it is necessary to use binding and protective materials for the fibrous layer. The fibres can be made into. yarn and then applied to the conductor in the form of a braid, but this is a slow and expensive process.

The fibrous layers heretofore available, except for the more expensive braids, have resistance to abrasion and tearing which is substantially no better than that of the slivers or rovings from which the layers are made. No one has provided a dense, seamless, uniformly felted core covering having substantial resistance to abrasion and tearing such as is commonly found in felts used for hats and table coverings.

This invention provides cores, and more specifically electrical conductors, having compact,

seamless felted jackets, which jackets comprise fibres variously and indiscriminately arranged and so interentangled and compacted as to form unitary fabric walls. The individual fibres comprising the jacket do not themselves extend in any one general direction, but extend in any and r completely interentangled and uniformly felted.

Because of this uniformity the jacket may be made extremely thin, or it may be built up uniformly to any practical thickness.

The felted jacket of this invention, being in fact a fabric and not merely a compressed layer of partially and incompletely interentangled fibres, is highly resistant to abrasion and to separation of the fibres. The resistance to separation is uniform in all directions. jacket may, because of these characteristics, be employed as the outer covering of electrical conductors, thereby eliminating in many instances the more expensive braids heretofore used.

This description refers to the forming of a felted jacket on an electrical conductor. It will be understood, of course, that there is no limitation, actual or implied, to forming the jacket immediately overlying the conductor itself. The felted jacket may be formed directly on the conductor, or it may be formed over another covering or coverings on the conductor. The fibres may be of any suitable material such, for example, as cotton, asbestos, flax, silk or other material. If desired, separate super-imposed layers of the same or different materials and thicknesses may be formed on the conductor, and these layers may or may not, as desired, be separated by intervening protective or coating materials.

Referring first to Fig. i, there is shown a core Si, in this embodiment an electrical conductor,

having a seamless, felted fibrous jacket which is highly resistant to abrasion and separation of the fibres. The felted layer may, if desired, be secured to the core 5i by a layer 82 of a suitable adhesive.

Fig. 2 discloses an insulated conductor construction in which the conductor is provided with a covering lid, for example a rubber compound, prior to the application of a felted fibrous jacket 85, similar to the jacket 82 of Fig. 1. If desired, the felted fibrous jacket may be adhesively secured to the underlying layer 86.

Fig. 3 shows a conductor construction in which the conductor 8% is provided with a plurality of overlying felted fibrous jackets 81 and 89, similar to the jacket 82 of Fig. 1, having protective coating layers 88 and 90. It will be understood that any desired number of overlying fibrous layers may be employed.

Figs. 4 to 13 of the drawings disclose one appa ratus which may be used for applying the felted fibrous jacket of this invention. Referring first to Figs. 4 to 7, it will be seen that the housing [I containing the greater part of the mechanism is for convenience mounted upon an angle-bar frame l2 supported upon standards l3.

As may best be seen in Fig. 5, a drive shaft and pulley (not shown), driven by any suitable source of power are connected by means of a belt indicated at H which passes from the driving pulley upwardly and over a pulley l5, downwardly and under a pulley Hi, again upwardly and over a pulley l1, and then downwardly'to the driving pulley. For reasons which will appear hereinafter, the driving connection is such that during operation the pulleys l5 and I! are rotated at 'a very high speed, while the pulley l5 desirably is rotated at a lower speed.

The pulley l6 conveniently is utilized through the medium of a variable, speed-reduction driving connection to drive a feeding roll for feeding a fieecy strand of fibres from a supply into the machine at a regular predetermined rate. As is The new felted best shown in Fig. 7, in theillustrative embodiment the pulley l6 is'ligidly secured on one end of a horizontal shaft l8 passing through and rotatably mounted in the lower portion of the housing I I. Referring now to Figs. 6 and 7, secured on the other end of the shaft I 8 is a worm I9 meshing with a worm wheel 20 secured on the lower end of a vertical shaft 2| which is rotatably mounted in a bracket 22 projecting from the housing II.

On the vertical shaft 2| is a roller 23 which is keyed to the shaft so as to rotate therewith but which is free to move longitudinally along the shaft. The periphery of the roller 23 frictionally engages the face of a disk 24 secured on one end of a horizontal shaft 25 passing through and rotatably mounted in the housing II. The disk 24 is resiliently pressed against the roller 23, as by means of a spiral spring 26 surrounding the shaft within the housing l 0. Also bearing against the face of the disk 26 is a roller 2'! mounted on a vertical shaft 28 aligned with and spaced slightly from the end of the shaft 20. The shaft 28 is rotatably mounted in a bracket 29 projecting from the housing H. The roller 2? is keyed to the shaft 28 so as to rotate therewith, but is free to move longitudinally along the shaft. It will be apparent that the shatf it acts through the medium of the roller 23 to turn the disk 26, and that rotation of the disk 23 causes the roller 2i and the shaft 28 to turn.

Means are provided for simultaneously sliding the rollers 23 and 27 on the shafts 2i, and 28 so as to vary inversely the distances of the rollers from the center of the disk 26, thereby permitting a wide range of variation in the relative speeds of the two shafts. Conveniently, such means comprises a block 3d having recesses 30 and 32 for receiving the wheels 23 and 21, the block 3d being mounted to slide vertically on a guide 33 mounted in the brackets 22 and 29.

.Vertical adjustment of the block 3@ may be made by means of the vertical screw 3 rotatably mounted in the brackets 22 and 29, and having screwthreaded engagement with a vertical opening through the block. conveniently the screw 35 projects upwardly beyond the bracket 29 and is provided with a control Wheel 35. It will be apparent that by turning the wheel 35 the block 30 may be raised or; lowered so as to move the rollers 23 and 21 over the face of the disk 24 toward and away from the center of the disk, thereby varying the speed of the shaft 28 relative to the speed of the shaft 2|.

Desirably the variable speed friction clutch arrangement just described is enclosed within a protecting casing 12 secured on'the end of the housing II. In the drawings the casing 12 is shown broken away in order to disclose the mechanism within.

The upper end of the vertical shaft 28 projects above the bracket 29 and has secured on its end a worm 36 meshing with a worm wheel 31 which is rigidly secured on one end of a shaft 38 passing through and rotatably mounted in the upper part of the housing 11.

As may best be seen in Figs. 8 and 11, secured on the shaft 38 within the casing II is a toothed feeding roll 39. The feeding roll 39, which normally rotates at a relatively slow speed, feeds a supply of fibrous material into the machine.

Conveniently the fibrous material is supplied in lap form wound into a roll 40. The roll 40 may be supported on a center rod 4| having on its ends grooved rollers 42. The rollers 42 rest on the upwardly inclined guides 43 projecting rearwardly from points on the housing slightly belowthe shaft 38. It will be apparent that the weight of the roll of fibrous material 40 will be suificient to keep the supply of material pressed against the feeding roll 39 at all times, and it will also be apparent that as the feeding roll 39 rotates it will remove the lap from the supply roll and feed the fibrous material into the machine. It may be desirable to provide the guides 43 with guard members 44 to aid in keeping the supply roll 40 in alignment.

As is best shown in Fig. 8, the cover 45 over the feed roll preferably is pressed resiliently toward the feed roll so as to insure uniform feeding of the fibrous material in the machine, as well as to hold the strand while the separating roll teeth tear the fibres of the strand apart. In the illustrative embodiment the cover 45 is provided with a handle 46, and has a limited freedom of movement toward and away from the feed roll along the guide pins 41. Spiral springs 48 surrounding the pins 41 normally press the cover 45 toward the feed roll, such movement being limitedby engagement of the handle 46 with the housing II to prevent actual contact between the cover 45 and the feed roll 39.

In place of the feeding roll shown in Figs. 8 and 11 it may be desirable in some cases to use a feeding roll having fine axial slots along its surface instead of teeth. Such a roll 39a is illustrated in Figs. 12 ,and 13, and merely by way of example the axial slots 39b may be inch wide.

36, inch deep and spaced V inch apart.

Referring particularly to Fig. 8, it will be seen that the fieecy strand of fibrous material picked up by the feeding roll 39 from the supply roll 40 is fed into a chamber 54 which contains the separating roll 49. The separating roll is rotatably mounted in the housing parallel to the feeding roll 39, and upon one end of the roll axle extending beyond the housing H is secured the pulley l5. During operation of the machine the separating roll is rotated at high speed, and the pins 50, projecting radially from the surface of the separating roll, tear apart the individual fibres of the fieecy strand, and project the separated fibres at high speed into the applicator chamber 52.

In order to attain substantially complete separation of the individual fibres comprising the fieecy strand the pins 59 preferably are numerous and somewhat widely spaced, and uniformly distributed over the roll, axially so that the paths of no two pins exactly coincide, and circumferentially so that the separated fibres will form a practically cofitinuous stream. The number of pins will depend upon the degree of separation of the fibres desired. A suitable arrangement comprises placing the pins in multiple spiral paths, as shown in Fig. 10, and desirably each pin is flattened at the tip to an edge parallel to the direction of motion. Since the separating roll 39 rotates very rapidly, and the feeding roll 39 rotates at a relatively low speed, the pins 50 will completely tear apart the fibres of the fieecy strand, and the separated fibres will be thrown off from the separating roll by centrifugal force into the applicator chamber 52.

As the separated fibres are thrown off from the separating roll 49 they are projected at high speed into the chamber 52. Mounted in the chamber 52 is an applicator 53 which collects the separated fibres and applies them in a multiplicity of overlying thin layers on the core 5| as the core moves lineally through the chamber. The applicator 53, as shown more fully in Figs. 7 and 9, is rotatably mounted in the chamber 52, with both of its ends extending beyond the housing Secured on one end of the applicator is the driving pulley l1, and during operation of the machine the applicator is rotated at high speed.

The applicator has an axial opening through which the core 5| passes, from right to left in Fig. 4. If desired, the core 5| may be coated with an adhesive, as by dipping it in a bath 55 of adhesive compound, before it enters the applicator.- The core is drawn through the applicator by means of a suitable take-up device 63.

As is more clearly shown in Fig. 9, the ends of the applicator desirably are provided with removable guide members 56 and 51, conveniently held in place by means of the nuts 59 and 59 screwthreadedly engaging and clamping the iongitudinally split ends 50 and 5| of the applicator. These guide members are replaceable by other members having different bores to permit the machine being used most advantageously for cores of different diameters and for fibrous jackets of diiferent thicknesses. Desirably, sealing means indicated at 62 protect the bearings of the applicator against abrasion from the fibres in the chamber 52.

Within the chamber 52 the applicator has one or more offset sections, there being three in the illustrative embodiment, which give to it a crank shape. Desirably these offset sections are designed so as to counterbalance each other. Each of the ofi'set sections is provided with a fiat surface 65 for collecting the separated fibres in the chamber 52, and desirably with means such as a series of closely spaced, curved, spring wire teeth 66 for conveying the collected fibres to the core and for pressing the fibres on to the core. The rapidly rotating applicator 53 collects the fibres on the surface 65 in the form of a loosely matted ribbon, the fibres so collected extending in any and all directions. As the applicator rotates, this thin ribbon of fibres is'drawn toward and wrapped around the core, and since the applicator rotates at a very high speed, the fibres will be applied to the core as it passes through the applicator in a multiplicity of overlying thin layers.

The spring teeth 66 press the thin ribbon of fibres on to the core as it is applied, and this compacting of the variously and indiscriminately arranged fibres produces in the composite a felted fabric jacket about the core which has substan tially uniform characteristics throughout its thickness.

In order to permit access to the separating roll and the applicator, the chambers 52 and 54 in the housing desirably are closed by a cover 68 hinged to the housing at 59. For convenience, a handle 10 is provided, and spring clips ll serve to keep the cover closed during operation.

The operation of the machine as a whole will now be summarized. The wire or other core 5| which is to be coated with fibrous material is moved lineally through the axial opening in the applicator. Conveniently, the wire is drawn through the machine by means of a power driven take-up device. The speed at which the wire is moved through the machine will depend upon the width of the machine, the speed at which the applicator rotates, and the thickness of the fibrous jacket which is to be applied. If desired, the wire may be coated with an adhesive just before it enters the machine.

The feeding roll 34, the separating roll I! and the applicator 53 all are rotated. The feeding roll is turning slowly, its driving connection including speed reduction mechanism, and also including means for accurately varying the speed of the feeding roll. The speed of the feeding roll will depend on the thickness and composition of the fieecy strand of fibrous material being .fed into the machine, the speed of the other moving elements of the machine, and the thickness of the fibrous jacket which is to be applied to the wire. It has been found that for insulating magnet wire in a machine as described the speed of the feeding roll desirably is variable over a range of from one turn per eighty feet of conductor to one turn per eight feet of conductor.

The fieecy strand of fibres, for example asbestos, desirably is supplied to the machine in The feeding roll conveys the fibrous strand from the supply package to the separating roll. The separating roll is set with pins desirably onequarter of an inch long or longer, and the separating roll is rotating at high speed. Deslrably, the speed of the separating roll will be such as to separate completely the individual fibres of the strand. Experimental data thus far obtained indicates that the speed in revolutions per min ute should be at least where D is the diameter of the roll in inches. The pins of the separating roll tear the fibres of the fieecy strand apart, and the fibres are thrown off from the separating roll by centrifugal force into the applicator chamber.

The high speed of the separating roll is necessary not only to tear the fibres apart, but also to insure that the separated fibres will be thrown off from the roll. If a few fibres should cling to the teeth, no harm will be done, for these fibres will be carried around and thrown off into the applicator chamber upon the next turn of the separating roll.

Within the applicator chamber, the applicator is turning at high speed, desirably as high as is practical for the structural strength of the applicator, for example about 6,000 revolutions per minute or more. Desirably this speed will be such as to give a pitch or angle of lay between the fibres and the conductor axis of about 65 degrees. The quality of the fibrous covering applied to the conductor is about proportional to the angle of lay between the fibres and the conductor.

The separated fibres which are thrown from the separating roll into the applicator chamber collect on the forward face of the applicator to form a thin, very loosely matted ribbon. The fibres so collected are variously and indiscriminately arranged, and extend in any and all directions. This ribbon is not a true fabric, but there is sufiicient cohesion between the fibres as they are pressed together by the rotating applicator so that as the applicator rotates the thin ribbon is wrapped around the conductor.

The applicator teeth, conveniently of curved spring wire and closely spaced, lay the ribbon of fibres on the conductor and press the ribbon into place. Thus it will be seen that a fibrous wall is built up of a wide, spirally wrapped, thin ribbon of fibres, the wall having a multiplicity of layers, and the spiral wrapping having a pitch which is very small compared to the width of the ribbon. The ribbon is continuously pressed on to the conductor as it is applied, and the wall which is formed becomes a unitary, seamless, inl tegrally felted covering in which the identity of the individual layers is lost.

The term "ribbon or layer does not necessarily denote a continuous sheet in theordinary sense because the individual fibres may be rather l widely separated to leave open spaces between them. There may even be absolute longitudinal discontinuity at times, either at any point across the width or entirely across the width. In general, the smaller the core the more sparse will be i the fibres in the ribbons, and the more rapid will be the rate of application. With large cores where the rubbing action of the applicator may be heavier the ribbon may be more nearly continuous, and the rate of application slower. But 2 in any case, some of the fibers of one layer will intermingle with the fibers of one or more underlying layers, and others of the fibers will intermingle with the fibers of one or more overlying layers so that in the finished article the layers 2 are integrally interfelted, so that the jacket is a tight, seamless unit which is uniform and homogeneous throughout its entire thickness and extent.

It will be noted that the applicator partially E obstructs the flow of fibres into the applicator chamber for a brief interval during each rotation. It has been found that this does not in any way interfere with the operation of the applicator in building up a unitary felted fibrous wall. The applicator is so designed that it tends to scoop up any fibres which may collect on the inner wall of the applicator chamber so that these fibres become a part of the ribbon being fed to the conductor. It will be noted also that as the applicator moves past the opening between the separating and applicator chambers, the separating roll will remove from the outer surface of the applicator any body of fibres which may have accumulated thereon. E

This invention provides cores of various sizes and shapes with unitary, seamless jackets of felted fibres. The methodand apparatus disclosed herein merely for illustrative purposes permit the application of an extremely thin jacket, or, if desired, the jacket may be built up to any practical thickness. In either case, the charact'er of the jacket is the same, notably a unitary felted covering having substantially uniform characteristics throughout its thickness.

The foregoing description of certain specific embodiments of the invention is illustrative merely, and is not intended as defining the limits of the invention.

1 claim:

1. In an insulated electrical conductor, a conducting core and a homogeneous, seamless, tubular, felted protective jacket therefor, said jacket comprising successive, generally circumferential laminations of indiscriminately intertangled, individually matted fibres providing a unitary felted insulating covering of substantially uniform density throughout its thickness, circumference and length, and uniformly resistant to separating forces in all directions. 1

2. In an insulated electrical conductor, a conducting core and a homogeneous, seamless, tubular, felted protective jacket therefor, said Jacket comprising successive, generally circum- 5 ferential laminations of indiscriminately intertangled, individually matted fibres providing a unitary felted insulating covering of predetermined thickness of substantially uniform density throughout its thickness, circumference and length, and uniformly resistant to separating forces inail directions.

SIDNEY E. BORGESON. 

